In equine medicine, the disease “podotrochlitis” or “podotrochlosis”, commonly also referred to as “navicular syndrome”, is a widespread disease in the distal section of the horse's forelimb. The traditional form of the disease has been described as a chronic, progressive and degenerative disease with involvement of the navicular bone, the navicular bursa and the flexor tendon.
In horses, genetic predisposition, inadequate keeping, poor or irregular training, severe strain and age frequently result in an atrophy of the navicular bone, which leads to a demineralization of the bone. The subchondral bone will then, as a result of the unphysiological pressure conditions which act on the bone, undergo osteoporotic change.
In the early stages of the disease, the subchondral bone comprises a large number of widened vascular ducts which are filled with granulation tissue and surrounded by osteoclasts and osteoblasts. During the pathogenesis, osteoclastic changes develop which approach the compact tissue of the tendons' gliding surface, whereby the latter becomes thin, and microfractures of the palmar compact tissue may result. This primarily gives rise to osteoclasis of the subchondral bone.
When these disease symptoms occur, a periodic chronic lameness results, and this leads in most cases to the horse's long-term unusability.